Without limiting the scope of the present invention, its background will be described with reference to steam injection into a hydrocarbon bearing subterranean formation, as an example. During the production of heavy oil, oil with high viscosity and high specific gravity, it is sometimes desirable to inject a recovery enhancement fluid into the reservoir to improve oil mobility. One type of recovery enhancement fluid is steam that may be injected using a cyclic steam injection process, which is commonly referred to as a “huff and puff” operation. In such a cyclic steam stimulation operation, a well is put through cycles of steam injection, soak and oil production. In the first stage, high temperature steam is injected into the reservoir. In the second stage, the well is shut to allow for heat distribution in the reservoir to thin the oil. During the third stage, the thinned oil is produced into the well and may be pumped to the surface. This process may be repeated as required during the productive lifespan of the well.
In wells having multiple zones, due to differences in the pressure and/or permeability of the zones as well as pressure and thermal losses in the tubular string, the amount of steam entering each zone may be difficult to control. One way to assure the desired steam injection at each zone is to establish a critical flow regime through nozzles associated with each zone. Critical flow of a compressible fluid through a nozzle is achieved when the velocity through the throat of the nozzle is equal to the sound speed of the fluid at local fluid conditions. Once sonic velocity is reached, the velocity and therefore the flow rate of the fluid through the nozzle cannot increase regardless of changes in downstream conditions. Accordingly, regardless of the differences in annular pressure at each zone, as long as critical flow is maintained at each nozzle, the amount of steam entering each zone is known.
It has been found, however, that achieving the desired injection flowrate and pressure profile by reverse flow through conventional flow control devices is impracticable. As the flow control components are designed for production flowrates, attempting to reverse flow through conventional flow control components at injection flowrates causes an unacceptable pressure drop. Accordingly, a need has arisen for a fluid flow control system that is operable to control the inflow of fluids for production from the formation. A need has also arisen for such a fluid flow control system that is operable to control the outflow of fluids from the completion string into the formation at the desired injection flowrate. Further, a need has arisen for such a fluid flow control system that is operable to allow repeated cycles of inflow of formation fluids and outflow of injection fluids.